In cellular systems today, voice, data and signaling traffic must be backhauled from the cell tower sites to the central office where the mobile switching center is located. In general, backhauling refers to getting data to the core network, e.g., between the base station and the base station controller. In some cases, backhauling may include sending network data over an out-of-the-way route (including taking it farther than its destination) in order to get the data to its destination sooner or at a lower cost. Currently, a majority of this backhaul takes place over dedicated T1 lines. There are also some wireless backhaul schemes used primarily in short range niche applications that utilize both licensed and unlicensed bands.
Cellular backhaul primarily utilizes dedicated T1 lines. The guaranteed bandwidth and latency are important to support real time voice calls. Typically, T1 slots are dedicated to particular voice circuits or data channels. Bandwidth efficiencies of using IP over the backhaul to aggregate traffic and dynamically adapt capacity to the varying demand for data and voice are available, but are not used in the majority of deployments today.
While there are several wireless backhaul technologies, the interface to these systems is typically made to look like a T1 line. This allows the same interfaces and time slot assignments to be used. The advantage of wireless backhaul is lower cost compared to leasing T1 lines, but the wireless systems are often limited in range and by terrain.
There has been interest in using the public internet to backhaul cellular traffic given the wide availability and relatively low cost of internet connections compared with dedicated T1 lines.
In some aspects, the invention includes a method for backhauling wireless voice and data transmissions. The method includes receiving, at a base station, a wireless transmission. The method also includes forwarding the transmission from the base station to a base station controller over a shared network.
Embodiments can include one or more of the following.
The method can include receiving, at the base station controller, a second transmission and forwarding the second transmission to the base station over the shared network. The shared network can be a non-private network. The shared network can be the internet.
The method can also include providing a jitter buffer at the base station controller and using the jitter buffer to compensate for jitter introduced by the shared network. The method can also include providing a jitter buffer at the base station and using the jitter buffer to compensate for jitter introduced by the shared network.
Forwarding the transmission can include forwarding the transmission using a secure protocol. The secure protocol can be SSL.
The method can also include determining a priority of the received transmission and forwarding the transmission based on the determined priority. Determining a priority can include assigning a first priority to voice transmissions and assigning a second priority to data transmissions. The first priority can be greater than the second priority.
Forwarding the transmission can include forwarding the transmission using voice over IP technology. The method can also include performing decryption of the transmission at the base station controller. The method can also include performing encryption of the second transmission at the base station controller. The method can also include performing power control at the base station. The transmission can be a transmission from a cellular telephone.
In additional aspects, the invention includes a method that includes receiving, at a base station, a wireless transmission from a first mobile unit to be routed to a second mobile unit. The method also includes determining if the second mobile unit is within a communication range of the base station and if the second mobile unit is within the range, locally routing the transmission from the first mobile unit to the second mobile unit at the base station.
Embodiments can include one or more of the following.
The method can include forwarding the transmission from the base station to a base station controller if the second mobile unit is not within the range. Forwarding the transmission from the base station to the base station controller can include forwarding the transmission from the base station to the base station controller over a shared network. The shared network can be the internet.
In additional aspects, the invention includes a system for backhauling wireless voice and data transmissions. The system includes a base station configured to receive a wireless transmission and forward the transmission to a base station controller over a shared network.
Embodiments can include one or more of the following.
The system can also include a base station controller configured to receive a second transmission and forward the second transmission to the base station over the shared network. The shared network can be the internet. The base station controller can include a jitter buffer configured to compensate for jitter introduced by the shared network. The base station can include a jitter buffer configured to compensate for jitter introduced by the shared network. The base station can be further configured to determine a priority of the received transmission and forward the transmission based on the determined priority.
In additional aspects, the invention includes a system that includes a base station. The base station is configured to receive a wireless transmission from a first mobile unit to be routed to a second mobile unit and determine if the second mobile unit is within a communication range of the base station. If the second mobile unit is within the range, the base station is configured to locally route the transmission from the first mobile unit to the second mobile unit at the base station.
Embodiments can include one or more of the following.
The system can also include a base station controller. The base station can be configured to forward the transmission to the base station controller if the second mobile unit is not within the range.
Advantages that can be seen in particular implementations include one or more of the following.
In some embodiments, using a software radio system can reduce the cost of cellular backhaul.
In some embodiments, the software radio system allows one to perform rapid experiments and any changes to the system or protocol can be software downloads to the infrastructure.
In some embodiments, the software radio system employs QoS measurements and mechanisms to ensure adequate bandwidth and latency to support voice and data user requirements.